diff --git a/src/main/java/JettyLauncher.java b/src/main/java/JettyLauncher.java
index 93f27ef..44c1acd 100644
--- a/src/main/java/JettyLauncher.java
+++ b/src/main/java/JettyLauncher.java
@@ -16,12 +16,17 @@
         System.setProperty("java.awt.headless", "true");
 
         String host = null;
-        int port = 8080;
+        String port = null;
         InetSocketAddress address = null;
         String contextPath = "/";
         String tmpDirPath="";
         boolean forceHttps = false;
 
+        host = getEnvironmentVariable("gitbucket.host");
+        port = getEnvironmentVariable("gitbucket.port");
+        contextPath = getEnvironmentVariable("gitbucket.prefix");
+        tmpDirPath = getEnvironmentVariable("gitbucket.tempDir");
+
         for(String arg: args) {
             if(arg.startsWith("--") && arg.contains("=")) {
                 String[] dim = arg.split("=");
@@ -31,13 +36,10 @@
                             host = dim[1];
                             break;
                         case "--port":
-                            port = Integer.parseInt(dim[1]);
+                            port = dim[1];
                             break;
                         case "--prefix":
                             contextPath = dim[1];
-                            if (!contextPath.startsWith("/")) {
-                                contextPath = "/" + contextPath;
-                            }
                             break;
                         case "--max_file_size":
                             System.setProperty("gitbucket.maxFileSize", dim[1]);
@@ -62,10 +64,14 @@
             }
         }
 
+        if (contextPath != null && !contextPath.startsWith("/")) {
+            contextPath = "/" + contextPath;
+        }
+
         if(host != null) {
-            address = new InetSocketAddress(host, port);
+            address = new InetSocketAddress(host, getPort(port));
         } else {
-            address = new InetSocketAddress(port);
+            address = new InetSocketAddress(getPort(port));
         }
 
         Server server = new Server(address);
@@ -143,6 +149,23 @@
         return new File(System.getProperty("user.home"), ".gitbucket");
     }
 
+    private static String getEnvironmentVariable(String key){
+        String value =  System.getenv(key.toUpperCase().replace('.', '_'));
+        if (value != null && value.length() == 0){
+            return null;
+        } else {
+            return value;
+        }
+    }
+
+    private static int getPort(String port){
+        if(port == null) {
+            return 8080;
+        } else {
+            return Integer.parseInt(port);
+        }
+    }
+
     private static Handler addStatisticsHandler(Handler handler) {
         // The graceful shutdown is implemented via the statistics handler.
         // See the following: https://bugs.eclipse.org/bugs/show_bug.cgi?id=420142
diff --git a/src/main/scala/gitbucket/core/plugin/PluginRegistry.scala b/src/main/scala/gitbucket/core/plugin/PluginRegistry.scala
index b633691..b018a29 100644
--- a/src/main/scala/gitbucket/core/plugin/PluginRegistry.scala
+++ b/src/main/scala/gitbucket/core/plugin/PluginRegistry.scala
@@ -15,7 +15,7 @@
 import gitbucket.core.service.RepositoryService.RepositoryInfo
 import gitbucket.core.service.SystemSettingsService
 import gitbucket.core.service.SystemSettingsService.SystemSettings
-import gitbucket.core.util.DatabaseConfig
+import gitbucket.core.util.{ConfigUtil, DatabaseConfig}
 import gitbucket.core.util.Directory._
 import io.github.gitbucket.solidbase.Solidbase
 import io.github.gitbucket.solidbase.manager.JDBCVersionManager
@@ -235,7 +235,7 @@
       .reverse
   }
 
-  lazy val extraPluginDir: Option[String] = Option(System.getProperty("gitbucket.pluginDir"))
+  lazy val extraPluginDir: Option[String] = ConfigUtil.getConfigValue[String]("gitbucket.pluginDir")
 
   def getGitBucketVersion(pluginJarFileName: String): Option[String] = {
     val regex = ".+-gitbucket\\_(\\d+\\.\\d+\\.\\d+(-SNAPSHOT)?)-.+".r
diff --git a/src/main/scala/gitbucket/core/service/SystemSettingsService.scala b/src/main/scala/gitbucket/core/service/SystemSettingsService.scala
index 8f4e50e..34d8fd1 100644
--- a/src/main/scala/gitbucket/core/service/SystemSettingsService.scala
+++ b/src/main/scala/gitbucket/core/service/SystemSettingsService.scala
@@ -305,7 +305,7 @@
   private val PluginProxyPassword = "plugin.proxy.password"
 
   private def getValue[A: ClassTag](props: java.util.Properties, key: String, default: A): A = {
-    getSystemProperty(key).getOrElse(getEnvironmentVariable(key).getOrElse {
+    getConfigValue(key).getOrElse {
       defining(props.getProperty(key)) { value =>
         if (value == null || value.isEmpty) {
           default
@@ -313,11 +313,11 @@
           convertType(value).asInstanceOf[A]
         }
       }
-    })
+    }
   }
 
   private def getOptionValue[A: ClassTag](props: java.util.Properties, key: String, default: Option[A]): Option[A] = {
-    getSystemProperty(key).orElse(getEnvironmentVariable(key).orElse {
+    getConfigValue(key).orElse {
       defining(props.getProperty(key)) { value =>
         if (value == null || value.isEmpty) {
           default
@@ -325,7 +325,7 @@
           Some(convertType(value)).asInstanceOf[Option[A]]
         }
       }
-    })
+    }
   }
 
 }
diff --git a/src/main/scala/gitbucket/core/util/ConfigUtil.scala b/src/main/scala/gitbucket/core/util/ConfigUtil.scala
new file mode 100644
index 0000000..af5f942
--- /dev/null
+++ b/src/main/scala/gitbucket/core/util/ConfigUtil.scala
@@ -0,0 +1,41 @@
+package gitbucket.core.util
+
+import gitbucket.core.util.SyntaxSugars.defining
+
+import scala.reflect.ClassTag
+
+object ConfigUtil {
+
+  def getConfigValue[A: ClassTag](key: String): Option[A] = {
+    getSystemProperty(key).orElse(getEnvironmentVariable(key))
+  }
+
+  def getEnvironmentVariable[A: ClassTag](key: String): Option[A] = {
+    val name = (if (key.startsWith("gitbucket.")) "" else "GITBUCKET_") + key.toUpperCase.replace('.', '_')
+    val value = System.getenv(name)
+    if (value != null && value.nonEmpty) {
+      Some(convertType(value))
+    } else {
+      None
+    }
+  }
+
+  def getSystemProperty[A: ClassTag](key: String): Option[A] = {
+    val name = if (key.startsWith("gitbucket.")) key else "gitbucket." + key
+    val value = System.getProperty(name)
+    if (value != null && value.nonEmpty) {
+      Some(convertType(value))
+    } else {
+      None
+    }
+  }
+
+  def convertType[A: ClassTag](value: String): A =
+    defining(implicitly[ClassTag[A]].runtimeClass) { c =>
+      if (c == classOf[Boolean]) value.toBoolean
+      else if (c == classOf[Long]) value.toLong
+      else if (c == classOf[Int]) value.toInt
+      else value
+    }.asInstanceOf[A]
+
+}
diff --git a/src/main/scala/gitbucket/core/util/DatabaseConfig.scala b/src/main/scala/gitbucket/core/util/DatabaseConfig.scala
index a2f6682..1401b8e 100644
--- a/src/main/scala/gitbucket/core/util/DatabaseConfig.scala
+++ b/src/main/scala/gitbucket/core/util/DatabaseConfig.scala
@@ -6,7 +6,6 @@
 import Directory._
 import ConfigUtil._
 import com.github.takezoe.slick.blocking.{BlockingH2Driver, BlockingJdbcProfile, BlockingMySQLDriver}
-import gitbucket.core.util.SyntaxSugars.defining
 import liquibase.database.AbstractJdbcDatabase
 import liquibase.database.core.{H2Database, MySQLDatabase, PostgresDatabase}
 import org.apache.commons.io.FileUtils
@@ -54,16 +53,14 @@
   lazy val minimumIdle: Option[Int] = getOptionValue("db.minimumIdle", config.getInt)
   lazy val maximumPoolSize: Option[Int] = getOptionValue("db.maximumPoolSize", config.getInt)
 
-  private def getValue[T](path: String, f: String => T): T = {
-    getSystemProperty(path).getOrElse(getEnvironmentVariable(path).getOrElse {
-      f(path)
-    })
+  private def getValue[T: ClassTag](path: String, f: String => T): T = {
+    getConfigValue(path).getOrElse(f(path))
   }
 
-  private def getOptionValue[T](path: String, f: String => T): Option[T] = {
-    getSystemProperty(path).orElse(getEnvironmentVariable(path).orElse {
+  private def getOptionValue[T: ClassTag](path: String, f: String => T): Option[T] = {
+    getConfigValue(path).orElse {
       if (config.hasPath(path)) Some(f(path)) else None
-    })
+    }
   }
 
 }
@@ -114,33 +111,3 @@
     }
   }
 }
-
-object ConfigUtil {
-
-  def getEnvironmentVariable[A](key: String): Option[A] = {
-    val value = System.getenv("GITBUCKET_" + key.toUpperCase.replace('.', '_'))
-    if (value != null && value.nonEmpty) {
-      Some(convertType(value)).asInstanceOf[Option[A]]
-    } else {
-      None
-    }
-  }
-
-  def getSystemProperty[A](key: String): Option[A] = {
-    val value = System.getProperty("gitbucket." + key)
-    if (value != null && value.nonEmpty) {
-      Some(convertType(value)).asInstanceOf[Option[A]]
-    } else {
-      None
-    }
-  }
-
-  def convertType[A: ClassTag](value: String) =
-    defining(implicitly[ClassTag[A]].runtimeClass) { c =>
-      if (c == classOf[Boolean]) value.toBoolean
-      else if (c == classOf[Long]) value.toLong
-      else if (c == classOf[Int]) value.toInt
-      else value
-    }
-
-}
diff --git a/src/main/scala/gitbucket/core/util/FileUtil.scala b/src/main/scala/gitbucket/core/util/FileUtil.scala
index a54b75a..1fc336a 100644
--- a/src/main/scala/gitbucket/core/util/FileUtil.scala
+++ b/src/main/scala/gitbucket/core/util/FileUtil.scala
@@ -92,16 +92,12 @@
     name
   }
 
-  lazy val MaxFileSize =
-    if (System.getProperty("gitbucket.maxFileSize") != null)
-      System.getProperty("gitbucket.maxFileSize").toLong
-    else
-      3 * 1024 * 1024
+  lazy val MaxFileSize: Long = {
+    ConfigUtil.getConfigValue[Long]("gitbucket.maxFileSize").getOrElse(3 * 1024 * 1024)
+  }
 
-  lazy val UploadTimeout =
-    if (System.getProperty("gitbucket.UploadTimeout") != null)
-      System.getProperty("gitbucket.UploadTimeout").toLong
-    else
-      3 * 10000
+  lazy val UploadTimeout: Long = {
+    ConfigUtil.getConfigValue[Long]("gitbucket.UploadTimeout").getOrElse(3 * 10000)
+  }
 
 }
diff --git a/src/main/scala/gitbucket/core/util/Validations.scala b/src/main/scala/gitbucket/core/util/Validations.scala
index 0402c72..65082de 100644
--- a/src/main/scala/gitbucket/core/util/Validations.scala
+++ b/src/main/scala/gitbucket/core/util/Validations.scala
@@ -8,7 +8,7 @@
   /**
    * Constraint for the identifier such as user name or page name.
    */
-  def identifier: Constraint = new Constraint() {
+  val identifier: Constraint = new Constraint() {
     override def validate(name: String, value: String, messages: Messages): Option[String] =
       if (!value.matches("[a-zA-Z0-9\\-_.]+")) {
         Some(s"${name} contains invalid character.")
@@ -22,19 +22,22 @@
   /**
    * Constraint for the password.
    */
-  def password: Constraint = new Constraint() {
-    override def validate(name: String, value: String, messages: Messages): Option[String] =
-      if (System.getProperty("gitbucket.validate.password") != "false" && !value.matches("[a-zA-Z0-9\\-_.]+")) {
+  val password: Constraint = new Constraint() {
+    lazy val validatePassword = ConfigUtil.getConfigValue[Boolean]("gitbucket.validate.password").getOrElse(true)
+
+    override def validate(name: String, value: String, messages: Messages): Option[String] = {
+      if (validatePassword == true && !value.matches("[a-zA-Z0-9\\-_.]+")) {
         Some(s"${name} contains invalid character.")
       } else {
         None
       }
+    }
   }
 
   /**
    * Constraint for the repository identifier.
    */
-  def repository: Constraint = new Constraint() {
+  val repository: Constraint = new Constraint() {
     override def validate(name: String, value: String, messages: Messages): Option[String] =
       if (!value.matches("[a-zA-Z0-9\\-\\+_.]+")) {
         Some(s"${name} contains invalid character.")
@@ -48,7 +51,7 @@
   /**
    * Constraint for the color pattern.
    */
-  def color = pattern("#[0-9a-fA-F]{6}")
+  val color = pattern("#[0-9a-fA-F]{6}")
 
   /**
    * ValueType for the java.util.Date property.